1. Field of the Invention
The invention relates to monocrystalline layers, to the processes of fabricating such layers and to the structures comprising a monocrystalline layer. More particularly, it relates to a process for manufacturing monocrystalline layers which occur in the form of thin films whose thickness is on the order of a micron and which extend over a significant surface, on the order of 1 cm.sup.2.
2. Description of the Prior Art
Thin monocrystalline layers have not been manufactured until the present except by the epitaxial process which consists of growing one such layer on the surface of an existing crystal of the same material as the said layer or of a material having a crystalline structure identical to or related to that of the layer to be grown. This process thus requires a special support. Furthermore, in general, the monocrystalline layer cannot be easily detached from the support.
In addition, it is practically impossible to fabricate thin monocrystalline films by polishing whose thickness is less than 5 microns for a surface on the order of a square centimeter.
French Pat. No. 2 144 881 as well as an article entitled "Growth of Single Crystals Through Interfacial Layers" appearing in the Journal of Crystal Growth, 26 (1974) 21-26 by Distler et al. both disclose a process of growing single crystals through interfacial layers. In effect a crystal seed is encased within an interfacial layer and a massive crystal is then grown around the seed. The purpose of both these processes is to produce a massive monocrystal having improved properties. However, the massive crystals produced cannot be easily separated from their seeds and their accompanying interfacial layers. Furthermore, because of their thickness these crystals are too large for a number of important applications where it would be advantageous to be able to arrange thin monocrystalline layers on a given support, which may, for example, be metallic or insulating.